1. Field of the Invention
The present invention refers to an optical sensor device, especially to an optical sensor device for use in a measuring and/or inspection apparatus.
2. Description of the Prior Art
Such an optical sensor device is suitable in particular for use in multi-coordinate measuring devices (CMD) having tactile, exchangeable sensors, but it can also be used in another structural form in relation to optical CMDs, multi-sensor CMDs, microscopes and other optical measuring and/or testing systems or apparatuses/devices.
Multi-coordinate measuring apparatuses are well-known in various different forms in the state of the art. Here, a distinction is drawn between CMDs with predominantly tactile sensors and CMDs with optical sensors or multi-sensors, wherein, in the latter case, the sensors are fixedly integrated and are not exchangeable by means of a corresponding change device.
Such a multi-coordinate measuring apparatus is shown for example in DE 38 06 686 A1. In that apparatus, both a contact-free measurement of an object to be measured and also a mechanically touching measurement of an object are possible by means of a multi-sensor sensing system. An optical sensor device is provided for contact-free measurement, and a mechanical sensing head is provided for mechanically touching measurement. Besides a video sensor, the optical sensor device also has a laser sensor for automatic contour detection of the object to be measured. The laser sensor disclosed in DE 38 06 686 A1 follows the surface contour of the object at a constant spacing and thus provides for contour detection in virtually real time, with a high level of accuracy. In the scanning mode, the z-axis is continuously re-adjusted so that the laser sensor remains constantly adjusted in the focal plane. The laser sensor operates as a trigger scanner without a dedicated linear measurement range, that is to say the scanning accuracy depends only on the speed of travel of the optical sensor or the order of magnitude of the servo lag error. A further limitation in terms of measurement accuracy is formed by what are referred to as speckles which are produced upon focusing of the coherent laser beam on optically rough surfaces (unevenness of the order of magnitude of the wavelength) and cause difficulties with or make impossible evaluation of the measurement signal of the laser sensor.
It is also known in measurement technology for measurements to be carried out with so-called white light sensors in which the above-indicated problem of the speckle patterns does not arise. White light measuring systems of that kind conventionally comprise a sensor head connected to a control unit by way of a flexible optical fibre. The control unit includes the light source, the receiver in the form of a spectrometer, a measurement data evaluation means, a data interface to external devices and the power supply. Measurement systems of that kind, however, cannot be used as exchangeable sensors for CMDs as they cannot be automatically exchanged by virtue of the large-volume control unit and the fixed connection between the sensor head and the control unit. Further, the conventional white light sensors cannot be used as TTL sensors in combination with microscope measuring objectives. Combined use with other sensor types also seems not to be possible.